Mesh implant for use in reconstruction of soft tissue defects

ABSTRACT

The present invention relates to a resorbable polymeric mesh implant, that is intended to be used in the reconstruction of soft tissue defects. The mesh implant comprises at least a first and a second material, wherein the second material is substantially degraded at a later point in time than the first material following the time of implantation. The mesh implant is adapted to have a predetermined modulus of elasticity that gradually is decreased until the mesh implant is completely degraded and subsequently resorbed. Due to the gradual decrease in the modulus of elasticity of the inventive mesh implant, the regenerating tissue may gradually take over the load applied to the tissue defect area.

TECHNICAL FIELD

The present invention relates to a resorbable polymeric mesh implant, apolymeric mesh implant kit, and the uses thereof. The mesh implant, aswell as the kit, is intended to be used in the reconstruction of softtissue defects. The mesh implant comprises at least a first material anda second material, wherein the second material is substantially degradedat a later point in time than the first material, following the time ofimplantation of the mesh implant. The mesh implant is adapted to have asubstantially constant modulus of elasticity during the primary woundhealing period, after which period the modulus of elasticity isdecreased until the mesh implant substantially looses its mechanicalproperties and subsequently is completely degraded and absorbed by thebody. Due to the gradual decrease in the modulus of elasticity of theinventive mesh implant, the regenerating tissue may gradually take overthe load applied to the tissue defect area until the mesh implant iscompletely resorbed. With the inventive mesh implant there is no longera need for inert, non-resorbable, long term supporting structures.

BACKGROUND ART

Within the field of surgical repair of soft tissue defects, use is oftenmade of a mesh implant made of a non-resorbable material that isinserted to cover the area of the tissue defect. The mesh implant isused in order to support the regenerating tissue, and in, e.g. herniadefects, it works by mechanical closure of the defect and by inducing astrong scar fibrous tissue around the mesh implant. Such a mesh implantis most often made of various plastics, which are known to staybiostable and safe for a number of years after implantation. However,introducing a foreign material into the human or animal body is mostoften accompanied with side effects like migration, chronicinflammation, risk of infection etc. The introduction of a relativelylarge plastic body is also likely to induce a foreign body-reactioncaused by the body's immune defence system. As a result, the meshimplant may crumple up and loose its tissue supporting function.

The above mentioned mesh implants are in particular used in the repairof defects in the abdominal wall, which may be a result from trauma,tumour resection, prolapse or hernia.

A hernia is an abnormal protrusion of a peritoneal-lined sac through themusculoaponeurotic covering of the abdomen, the most common site for ahernia being the groin. Types of hernia are, among others, inguinalhernia or a femoral hernia, hiatal hernia, umbilicial hernia andincisional hernia, the latter being a hernia that pushes through a pastsurgical incision or operation.

One suggested theory in the field is that some patients, due to collagenmetabolic disorders, have a genetic predisposition for developingrecurrent hernias. An altered ratio of collagen types I and III in thesepatients, with an increase in collagen type II, is believed to reducethe mechanical strength of connective tissues. The decreased tensilestrength of collagen type III plays a key role in the development ofincisional hernias, see KLINGE, U, et al. Abnormal collagen I to IIIdistribution in the skin of patients with incisional hernia. Eur SurgRes. 2000, vol. 32, no. 1, p. 43-48.

It is in particular in the cases of large or recurrent hernias that thesurgical repair or herniorrhaphy makes use of an inert, non-resorbablemesh implant, as described above. The mesh implant is inserted to coverthe area of the abdominal wall defect without sewing together thesurrounding muscles. This can be done under local or general anesthesiausing a laparoscope or an open incision technique.

Among the laparoscopic techniques used, are the trans-abdominalpre-peritoneal (TAPP) technique and the totally extra-peritoneal (TEP)technique. With the TAPP technique, the pre-peritoneal space is accessedfrom the abdominal cavity, whereupon the mesh implant is placed betweenthe peritoneum and the transversalis fascia. With the TEP technique, themesh implant is again placed in the retroperitoneal space, but the spaceis accessed without violating the abdominal cavity. An open and minimalinvasive technique is the Lichtenstein hernia repair technique, in whichthe upper edge of the mesh implant is attached to the outer side of theinternal oblique and the lower edge of the mesh implant is attached tothe aponeurotic tissue covering the pubis.

Another open minimal invasive technique is the mesh-plug techniquecomprising attaching a mesh implant, as described above in reference tothe Lichtenstein technique, but also inserting a plug pushing theperitoneum in a direction towards the abdominal cavity.

The mesh implant, inserted with any of the above described techniques,is used in order to support the regenerating tissue with minimaltension. It works by mechanical closure of the defect in the abdominalwall and by inducing a strong scar tissue around the mesh implantfibres. The commercially available hernia mesh implants are often madeof various, inert, non-resorbable plastics, typically polypropylene, andsuffers from the same disadvantages, as described above in connectionwith mesh implants used for reconstruction of soft tissue defects ingeneral. However, implantation of large pieces of mesh implants in theabdominal wall cavity, also leads to considerable restriction thereof.In a study performed by Junge et al, JUNGE, K, et al. Elasticity of theanterior abdominal wall and impact for reparation of incisional herniasusing mesh implants. Hernia. 2001, no. 5, p. 113-118, the elasticity ofthe abdominal wall was measured and compared to that of commerciallyavailable non-resorbable hernia mesh implants. It was assumed that theflexibility of the abdominal wall is restricted by extensiveimplantation of large mesh implants, the more so if the mesh implantsare integrated into scar tissue. In addition, the unphysiologicalstretching capability of the mesh implants contrast with the highlyelastic abdominal wall and can give rise to shearing forces, favouringincreased local remodelling and thus recurrence at the margin. It wasconcluded that mesh implants used for repairing inscisional herniashould have an elasticity of at least 25% in vertical stretching and 15%in the horizontal stretching when subjected to a tensile strength of 16N/cm, in order to achieve almost physiological properties.

The progress within hernia repair mesh implant development, as well asin the development of mesh implants for the use of reconstruction ofsoft tissue defects in general, has been towards mesh implants with lessmass in order to minimize foreign body reactions, and larger pore sizes,which on one hand reduce the mass of the mesh implant and on the otherfacilitate ingrowth of tissue.

U.S. Pat. No. 6,319,264 B (TÖRMÄLÄ) Nov. 20, 2001 describes a porous,flexible and fibrous hernia mesh, which is intended to be implantedclose to hernia defects. The mesh comprises two functional layers,wherein the first layer is a rapidly degradable polymer layer facing thefascia, and wherein the second layer is a more slowly degradable polymerlayer. The first polymer layer has a fast resorption profile,approximately 14 days, said first layer promotes scar tissue formationdue to inflammatory reactions induced by the polymer degradation and dueto the porous structure of the first layer. The second polymer layer hasa longer resorption time, approximately 6 months, and thus supports thearea until the scar tissue is strong enough to resist pressure andprevent recurrent hernia formation. An optional third dense, thin,bioabsorbable layer is described, which prevents agents that could causetissue to tissue adhesion from moving from the hernia area through themesh and onto the surrounding tissue during the first weeks after theoperation. The mesh described in U.S. Pat. No. 6,319,264 acts as atemporary support until connective scar tissue has strengthened enoughand can replace the mesh, when the second layer finally degrades.

However, U.S. Pat. No. 6,319,264 is silent as to the load situationfound over the tissue defect area and to the modulus of elasticity ofthe hernia mesh. In the above described mesh, only the second layer isdesigned to support the tissue during the regenerative phase. The meshmaterial is by the body regarded as an inert material, in that no majorchanges in mechanical properties are observed until degradation hasreached to such a point where the material starts to crack with a moreor less catastrophic change in mechanical properties taking place.

It is known that the primary wound healing usually occurs over a timeperiod of 14 days followed by a remodelling period, which may extend upto and over 6 months. During this remodelling period, the newly formedtissue will undergo several phases, during which the tissue graduallybecomes more specific to support the various stress situations found inthe area. The inventors of the present invention therefore suggest thata device used to temporarily support the tissue defect in the area wherethe tissue is exposed to various stress situations should be so designedas to allow the newly formed tissue to gradually take over the loadduring the remodelling phase and thus build up the strength andcompliance needed to take over the full load once the support from thetemporarily implanted device is lost. Following the teachings of Jungeet al, a mesh implant used for reconstruction of soft tissue defects,should have an elasticity that is compatible with the elasticity of thesurrounding tissue, so that the flexibility of said tissue is notsubstantially restricted.

DISCLOSURE OF THE INVENTION

The object of the present invention is therefore to provide a resorbablemesh implant for use in reconstruction of soft tissue defects, themechanical properties of which stimulates the ingrowing, regeneratingtissue, and at the meantime allowing the regenerated tissue to graduallytake over the load found in the tissue defect area until the meshimplant substantially looses it mechanical properties and subsequentlyis completely resorbed. Another object of the present invention is toprovide a polymeric mesh implant kit. Still another object is to providea use of such a mesh implant and use of such a kit in the reconstructionof soft tissue defects.

These objects are achieved by the present invention according to thepreambles of the independent claims and provided with the featuresaccording to the characterizing portions of the independent claims.Preferred embodiments of the present invention are set forth in thedependent claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 schematically shows an embodiment of the present invention,wherein the mesh implant comprises two materials A and B,

FIG. 2 schematically shows an alternative embodiment of the presentinvention, wherein the mesh implant comprises three materials A-C,

FIG. 3 schematically shows a cross section of one structural design ofthe embodiment shown in FIG. 3,

FIG. 4 shows the modulus of elasticity of the mesh implant shown in FIG.1 as a function of time (not to scale),

FIG. 5 shows the modulus of elasticity of the mesh implant shown inFIGS. 2 and 3 as a function of time (not to scale).

An embodiment of the present invention is shown in FIG. 1, wherein themesh implant comprises two resorbable polymeric materials, material Aand material B. Material A is characterized by a time of substantialdegradation, t_(A), and a modulus of elasticity, E_(A). Consequently,material B is characterized by a time of substantial degradation, t_(B),and a modulus of elasticity, E_(B). Material B is substantially degradedat a later point in time, following the time of implantation of the meshimplant, than material A, i.e. t_(A)<t_(B). The time of substantialdegradation herein being defined as the point in time at which thematerial substantially loses its mechanical properties, or itsmechanical integrity, even though fragments of the material may still bepresent in the body. That is, the point in time at which the mechanicalintegrity of the material no longer provide the mesh implant withmechanical properties that contribute to the object of the inventivemesh implant. For instance, the mechanical properties of the materialmay have been lost at the time of substantial degradation, so that themechanical strength of the material is less than approximately 30% ofits initial strength.

The modulus of elasticity of material A is significantly higher than themodulus of elasticity of material B, i.e. E_(A)>E_(B), and consequently,the elongation of material A is significantly lower than the elongationof material B. It is here understood that E_(A) and E_(B) is the modulusof elasticity of the respective material in the present configuration.Thus, a material A will, for example, generally have a lower E_(A) ifthe material A is designed as having a perforated structure than if thesame material A exhibits a homogenous structure. For the differentmaterials of the inventive mesh implant, a modulus of elasticity ispreferably within the range of 300 kPa-3 GPa. It is to be noted that themodulus of elasticity of a material need not to have the same value inall directions, thus the modulus of elasticity in for instance thevertical direction need not to be identical with the modulus ofelasticity in the horizontal direction. t_(A) is in the time range of 14days-1 month after the time of implantation, i.e. t=t₀, and t_(B) is atleast 3-18 months after the time of implantation, preferably in the timerange of 6-12 months. Here it is also noted that even though it may bedifficult to exactly determine a specific time of substantialdegradation for a certain material A, the substantial degradation timet_(A) may for instance be accompanied with some uncertainty, forinstance ±5 days, this uncertainty is insignificant in comparison withthe much longer substantial degradation time frame of the secondmaterial B.

In the mesh implant according to the embodiment described above,material A and material B can be structurally designed as two separateperforated layers, respectively, arranged on top of each other. Also,material A and material B can be partly of fully incorporated with eachother, which will be explained in further detail below. Afterimplantation the mesh implant can be fixed with for instance suitablesutures, staples, fixation, pins, adhesives or the like. In someapplications of the implant, the pressure from the surrounding tissuemay be enough for initial fixation until newly regenerating tissueanchors the implant by tissue trough growth.

Material A acts as an initial and temporary support during the primarywound healing time period t=t₀-t_(A), during which E_(A) is high andsubstantially constant, allowing the elongation of the mesh implant tobe no more than in the range of 0 to 20%, but more preferably in therange of 0-10%.

Material A is substantially degraded at time t_(A), leaving material Bto alone carry the load applied to the tissue defect area. However, dueto the significantly lower modulus of elasticity of material B, part ofthe load will be transferred onto the surrounding and ingrowing tissue.The mechanical stimulation of the wound area will thus stimulate thecells to deposite new extracellular matrix as well as stimulateremodelling of the existing tissue to be oriented according to theexisting load pattern and gradually take over the load carried by themesh implant during the time period of t_(A)-t_(B). Thus, material Bfacilitates the mechanical stimulation of the surrounding tissue, e.g.aponeurotic structures, to develop the strength needed to finally takeover the total load applied to the tissue defect area when the meshimplant is substantially degraded and subsequently completely resorbed.

FIG. 4 shows the modulus of elasticity, E, of the mesh implant shown inFIG. 1 comprising material A and material B, as a function of time, t.During t=t₀-t_(A), material A practically carries the entire load overthe tissue defect area due to the higher modulus of elasticity of saidmaterial. E is substantially constant with respect to time and thuscorresponds to E_(A) during said time period. As described above, E isduring the time period of t=t₀-t_(A) high enough not to allow anysubstantial elongation of the mesh implant. A more or less suddendecrease in E is observed around t=t_(A) when material A issubstantially degraded. During t=t_(A)-t_(B), E=E_(B) since the loadover the tissue defect area is carried by material B alone, as describedabove. Preferably, E_(B) corresponds to an elongation of the meshimplant that is compatible with the elasticity of the surroundingtissue, so that the flexibility of said tissue is not substantiallyrestricted.

In an alternative embodiment of the inventive mesh implant, the meshimplant comprises a third resorbable polymeric material C, characterisedby t_(C) and E_(C) with t_(A)<t_(B)<t_(C), and E_(A)>E_(B)>E_(C). Alsohere it is understood that E_(C) is the modulus of elasticity ofmaterial C in its present configuration, as explained above. Thus, themesh implant comprises in the alternative embodiment three materials A,B and C. In said alternative embodiment the materials A through C can bestructurally designed as three separate perforated layers, arranged ontop of each other, as seen in FIG. 3. The materials A through C can alsobe partly or fully incorporated with each other, as explained in furtherdetail below. Two of the materials can be partly or fully incorporatedwith each other, but not the third, wherein any combination of materialsmay be possible.

When the mesh implant according to the alternative embodiment isinserted into the body (see discussion above that refers to implantationof the mesh implant according to the embodiment comprising material Aand B) material A, due to its high modulus of elasticity, acts as aninitial and temporary support during the primary wound healing timeperiod t=t₀-t_(A). Material A is substantially degraded at time t_(A),at which time material A substantially looses its mechanical properties,as described above. Material B, due to its significantly higher modulusof elasticity than material C, then carries the load applied to thetissue defect area, but due to the significantly lower modulus ofelasticity of material B than of material A, part of the load will betransferred onto the surrounding and ingrowing tissue. At time t_(B)material B is substantially degraded, leaving material C to carry theload applied to the soft tissue defect area. Due to the even lowermodulus of elasticity of material C, further load will be transferred tothe surrounding tissue. As described above, material B and material Cthus allow a biomechanical stimulation on the tissue, that will enableit to regenerate and remodel into a load bearing tissue, e.g.aponeurotic structures, tendons or ligaments, that gradually will takeover the load carried by the mesh implant during the time period oft_(A)-t_(C).

E as a function of time for the alternative embodiment shown in FIGS. 2and 3, is shown graphically in FIG. 5. t_(A) is, as in the embodimentshown in FIG. 1, approximately 14 days-1 month, and t_(C) is at least3-18 months after the time of implantation, preferably in the time rangeof 6-12 months. t_(B) can thus be anywhere between 14 days and 18months, as long as t_(A)<t_(B)<t_(C). In said alternative embodiment,material C acts as the last substantially degraded material of the meshimplant and E_(C) preferably corresponds to an elongation of the meshimplant that is compatible to the elasticity of the surrounding tissue,so that the flexibility of said tissue is not substantially restricted.Thus, E_(B) can have a predetermined value anywhere between E_(A) andE_(C).

The mesh implant according to the present invention, thus strives toimitate the ideal E versus t situation, shown as a dotted line in FIGS.4 and 5, of a resorbable mesh implant used to temporarily support softtissue defects during reconstruction thereof. In the ideal situation, Eof the mesh implant is during the primary wound healing time periodsubstantially constant and high enough not to allow any substantialelongation of the mesh implant, whereupon the mesh implant is degradedwith a gradual decrease in E so that the newly formed tissue maygradually take over the load applied to the tissue defect area duringthe remodelling phase. In the ideal situation, the mesh implant thusbiomechanically stimulates the surrounding tissue to build up thestrength and compliance needed to take over the full load once thesupport from the temporarily implanted device is lost after at least3-18 months. During the final stage of the remodelling phase, themodulus of elasticity of the mesh implant preferably corresponds to anelongation of the mesh implant that is compatible with the elasticity ofthe surrounding tissue, so that the flexibility of said tissue is notsubstantially restricted. The modulus of elasticity of various softtissues varies over a broad range from tendons having elastic modulusaround 700 MPa to very low modulus found in elastine rich tissue wheremodulus can be around 300 kPa. The modulus above is only approximatevalues due to the often non-linear behaviour of soft tissue. If theinventive mesh implant is intended to be used in the reconstruction ofdefects in the abdominal wall, following the teachings of Junge et al,the elasticity of the mesh implant, during the final stage of theremodelling phase, preferably corresponds to an elongation of 18-32%when subjected to a load of 16 N/cm.

Since a high modulus of elasticity of the mesh implant corresponds to alow elongation thereof, the ideal situation can just as well bedescribed by ways of elongation of the mesh implant as a function oftime. In that case the mesh implant is preferred to have a very low andsubstantially constant elongation during the primary wound healingperiod followed by a gradual increase in elongation. During the finalstage of the remodelling phase, the mesh implant preferably has anelongation as described above.

The inventive mesh implant can thus comprise any number of materials, aslong as it strives to imitate the ideal E versus t situation. However,due to manufacturing reasons, the number of materials are preferably notmore than five and more preferred 3-4.

In yet an alternative embodiment of the inventive mesh, the mesh implantaccording to any of the above described embodiments, can comprise afurther resorbable polymeric material D (not shown), which hasessentially the same characteristics as material A, with respect to timeof substantial degradation, t_(D). Material D can, in fact, be the samematerial as material A, but present in another configuration such thatE_(D) is not equal to E_(A). Material D is adapted to provide an extrasupportive structure during t=t₀-t_(A) and enables more ingrowth offibrous tissue. Material D can be structurally designed as a separateperforated layer or can be partly or fully incorporated with any of theother materials of the mesh implant, see further discussion below.

The mesh implant can also be provided with still a further material E(not shown), which material E is substantially degraded approximately atthe same point in time as any of the other materials present in the meshimplant, and thus in fact be the same material as any of the other saidmaterials. Material E can be present in another configuration than thatof the material with which it has approximately the same time ofsubstantial degradation, so that E_(E) is not equal to the modulus ofelasticity of that material, or material E can have approximately thesame modulus of elasticity as that material. Material E can bestructurally designed as a separate perforated layer or can be partly orfully incorporated with any of the other materials of the mesh implant,see further discussion below.

Optionally a thin resorbable film (not shown) can be applied to the meshimplant, in any of the above described embodiments, in order to preventadhesion of the mesh implant to surrounding tissues. If the mesh implantis intended to be used in the repair of abdominal wall defects, the thinfilm is preferably applied on the surface of the mesh implant facingtowards the abdominal cavity in order to in particular prevent adhesiononto the intestines. Said film is preferably a thin hydrophilic film,for instance a carbohydrate film, with a thickness in the range of 1-300microns, that forms a hydrogel structure when the film is brought intocontact with fluids contained in the tissue.

The inventive mesh implant preferably has mechanical properties thatenables it to be inserted into the body with any conventionally usedtechnique for implantation of mesh implants used for reconstruction ofsoft tissue defects, for instance any of the techniques described inreference to the implantation of hernia mesh implants. A mesh implant isherein being defined as an implant device with any type of through goingperforation, including pores, naturally occurring perforations orartificially created perforations, which extend from the proximalsurface to the distal surface of the implant device, so that there is acommunication between said proximal and distal surface. The materials ofthe inventive mesh implant, can be fibres made from any bioresorbablepolymer, copolymer, polymer blend or polymer composite, or can becombined assorted bioresorbable polymer parts, as long as the materialshave suitable predetermined times of substantial degradation and modulusof elasticity, so that when the materials are combined, the inventivemesh implant strives to imitate the ideal E versus t situation of aresorbable mesh implant used to temporarily support soft tissue defectsduring reconstruction, as described above.

Non-limiting examples of such synthetic resorbable materials are variouscombinations of the monomers glycolide, lactide and all stereoismerstherof, trimethylene carbonate, epsilon-caprolactone, dioxanone ordioxepanone. Depending on the desired mechanical properties and thechoice of manufacturing method, several of the homopolymers orcopolymers containing two or more of the above-mentioned monomers can beused to manufacture the mesh structure. Yet other examples of syntheticresorbable polymers that can be utilized are various aliphaticpolyurethanes, such as polyureaurethanes, polyesterurethanes andpolycarbonateurethanes, and also materials such as polyphosphazenes orpolyorthoesters.

The materials of the inventive mesh implant can have a woven or knittedstructure with pores of a suitable pore size, or can have a non-woven,for instance electro-spun, structure, wherein the (electro-spun)non-woven structure can further be furnished with man made through andthrough holes. When two or more materials are incorporated with eachother, fibres of said materials, respectively, can be jointly woven,knitted or non-woven into the same suitable structure. Also variousmaterials can be spun into fibres which are braided, twisted into amultifilament produced from two or more materials, which multifilamentis woven, knitted or non-woven into said suitable structure. Preferablyhowever, material A, and D, has, or is incorporated into, a porous,woven or knitted structure with a pore size preferably in the range of50-4000 microns, or a non-woven, for instance electro-spun structure,since a porous structure with a pore size in the above mentioned range,or a non-woven structure, enable for fibroblasts and other connectivetissue cells to grow into the pores, or into the non-woven structure,during the primary wound healing period. However, material A and D, neednot to have, or be incorporated into, the same structural design, thusmaterial A can have, or be incorporated into, a woven or knittedstructure while material D has, or is incorporated into, a non-wovenstructure and vice versa.

The last substantially degraded material of the inventive mesh implant,preferably has, or is incorporated into, a porous woven or knittedstructure, with a pore size preferably in the range of 0.5-4 mm, morepreferred 1-3 mm, in order to minimize the mass of the mesh implant aswell as maximizing the tissue supporting effect of said lastsubstantially degraded material.

Any other material can have, or be incorporated into, either a porouswoven or knitted structure, or a non-woven, for instance electro-spunstructure. If said materials have, or are incorporated into, a porouswoven or knitted structure it is preferred, however not mandatory, thatalso this structure has a pore size in the range of 0.54 mm, morepreferred 1-3 mm for reasons as described above.

The mesh implant can also be provided with trough going macro-pores,that extend from the proximal surface to the distal surface of the meshimplant, in order to further facilitate the communication between theproximal and distal surfaces of the mesh implant. Shown schematically inFIG. 3, is a cross section of a possible structural design of theinventive mesh implant comprising materials A, B and C, wherein materialA has a non-woven structure on top of material B and C, which areincorporated with each other into a woven or knitted, porous structure.However, it is pointed out that the structural design shown in FIG. 3,is not preferred to the other possible structural designs of theinventive mesh implant.

The inventive mesh can further comprise bioactive or therapeuticsubstances naturally present in humans or of foreign origin. Thesesubstances include, but are not limited to, proteins, polypeptides,peptides, nucleic acids, carbohydrates, lipids or any combinationsthereof. Especially considered are growth factors, such as PDGF, TGF orFGF, or components of the naturally occurring extracellular matrix,including cytokines, fibronectins, collagens, and proteoglycans such ashyaluronic acid. Therapeutic substances that are considered include, butare not limited to, antibiotic drugs and pain relieving substances.Bioactive or therapeutic substances of human or foreign origin can beentrapped within the porous structure of the implant or incorporatedthrough covalent or other chemical or physical bonding, in an activestate or as precursors to be activated upon any physical or chemicalstimuli or modification.

The present invention also refers to a polymeric mesh implant kit. Thekit comprises at least a first and a second material, wherein themodulus of elasticity of the second material is lower than the modulusof elasticity of the first material and wherein the second material issubstantially degraded at a later point in time than the first material,however any number of the above mentioned materials can be present inthe kit. The materials are provided in the kit as separate structurallydesigned layers and/or as materials fully or partly incorporated witheach other, wherein any combination of materials is possible, by meansof any of the above described ways. Each material has a predeterminedmodulus of elasticity in its present configuration, as defined above,and a predetermined time of substantial degradation, as defined above.Thus, the user of the kit can combine any number of materials into apolymeric mesh implant, as defined above and that strives to imitate theideal E versus t situation described above with reference to FIGS. 4 and5, that is tailored for each individual patient and for said patientsspecific needs, depending on the nature of the soft tissue defect to berepaired. At least one of the materials preferably has a time ofsubstantial degradation within the time range of 14 days-1 month, andpreferably has a predetermined modulus of elasticity that does not allowan elongation of the mesh implant, once combined, to be no more than inthe range of 0-20%, preferably no more than in the range of 0-10%. Atleast one of the materials preferably has a time of substantialdegradation within the time range of 3-18 months, preferably 6-12months, and preferably has a modulus of elasticity that corresponds toan elongation of the mesh implant, once combined, that is compatiblewith the elasticity of the surrounding tissue, so that the flexibilityof said tissue is not substantially restricted. As described above, thematerials can have a porous, woven or knitted, or a non-woven, forinstance electro-spun structure, wherein the (electro-spun) non-wovenstructure can further be furnished with man made through and throughholes. At least one of the materials, or at least one combination ofmaterials, can be provided with a thin resorbable film, preferably athin hydrophilic film as described above, in order to prevent adhesionof the mesh implant, once combined, onto surrounding tissue. Said filmcan also be provided in the kit as a separate item and be combined withthe selected materials, so that the mesh implant, once combined, isprovided with said film for the above mentioned reason. Preferably, atleast one of the materials of the kit that have a time of substantialdegradation within the time range of 14 days-1 month, has a porousstructure with a pore size in the range of 50-4000 microns or has anon-woven, for instance electro-spun structure, for reasons as describedabove. Preferably at least one of the materials of the kit that have atime of substantial degradation within the time range of 3-18 months,has a porous structure with a pore size in the range of 0.5-4 mmmicrons, more preferred 1-3 mm, for reasons as described above. Further,at least one of the materials, or at least one combination of materials,of the kit can comprise bioactive or therapeutic substances naturallypresent in humans or of foreign origin, as described above.

However, it is understood that the skilled person is capable of choosingsuitable materials, as defined above, in order to construe a polymericmesh implant that is tailored for each individual patient and for saidpatients specific needs, depending on the nature of the soft tissuedefect to be repaired, without having at hand the inventive kit.Therefore, the present invention also encompass the tailoring of aspecific polymeric mesh implant for the specific soft tissue defect tobe reconstructed, by choosing and combining suitable materials.

It will be understood that the invention is not restricted to the abovedescribed exemplifying embodiments thereof and that severalmodifications are conceivable within the scope of the following claims.

1. A resorbable polymeric mesh implant for use in reconstruction of softtissue defects, wherein the mesh implant comprises at least a firstmaterial and a second material, wherein the second material issubstantially degraded at a later point in time than the first materialcharacterized in that the modulus of elasticity of the mesh implant issubstantially constant and equal to the modulus of elasticity of thefirst material following the time of implantation and until said firstmaterial is substantially degraded, and in that the modulus ofelasticity of the mesh implant is substantially equal to the secondmaterial after the first material is substantially degraded, wherein themodulus of elasticity of the second material is lower than the modulusof elasticity of the first material.
 2. A mesh implant according toclaim 1, characterized in that the mesh implant comprises a thirdmaterial that is substantially degraded at a later point in time thanthe second material and has a significantly lower modulus of elasticitythan the second material and in that the modulus of elasticity of themesh implant is substantially equal to the third material after thesecond material is substantially degraded.
 3. A resorbable polymericmesh implant according to claim 1, characterized in that the lastsubstantially degraded material has a modulus of elasticity that iscompatible with the elasticity of the surrounding tissue so that theflexibility of said tissue is not substantially restricted.
 4. Aresorbable polymeric mesh implant according to claim 1, characterized inthat the first substantially degraded material is substantially degradedat a point in time within the time range of 14-30 days followingimplantation.
 5. A resorbable polymeric mesh implant according to claim1, characterized in that the last substantially degraded material issubstantially degraded at a point in time within the time range of 3-18months following implantation.
 6. A resorbable polymeric mesh implantaccording to claim 1, characterized in that the mesh implant is providedwith a further material, which further material is substantiallydegraded approximately at the same point in time as the firstsubstantially degraded material.
 7. A resorbable polymeric mesh implantaccording to claim 1, characterized in that the mesh implant is providedwith still a further material, which material is substantially degradedapproximately at the same point in time as any of the other materialspresent in the mesh implant.
 8. A mesh implant according to claim 1,characterized in that the materials are chosen in order to construe amesh implant that is tailored for the specific soft tissue defect to bereconstructed.
 9. A resorbable polymeric mesh implant according to claim1, characterized in that the mesh implant is provided with a resorbablefilm in order to prevent adhesion of the mesh implant onto surroundingtissue.
 10. A resorbable polymeric mesh implant according to claim 9,characterized in that the resorbable film is a hydrophilic carbohydratefilm.
 11. A resorbable polymeric mesh implant according to claim 1,characterized in that the first substantially degraded material and/orthe further material has or is incorporated into a woven or knitted,porous structure with a pore size in the range of 50-4000 microns.
 12. Aresorbable polymeric mesh implant according to claim 1, characterized inthat the first substantially degraded material and/or the furthermaterial has or is incorporated into a non-woven structure.
 13. Aresorbable polymeric mesh implant according to claim 12, characterizedin that the non-woven structure is an electro-spun structure.
 14. Aresorbable polymeric mesh implant according to claim 1, characterized inthat the last substantially degraded material has a woven or knitted,porous structure with a pore size in the range of 0.5-4 mm.
 15. Aresorbable polymeric mesh implant kit, comprising at least a first and asecond material, wherein the modulus of elasticity of the secondmaterial is lower than the modulus of elasticity of the first materialand wherein the second material is substantially degraded at a laterpoint in time than the first material, said materials are intended to becombined into a mesh implant according to claim 1 that is tailored forthe specific soft tissue defect to be reconstructed.
 16. A resorbablepolymeric mesh implant kit according to claim 15, characterized in thatthe kit comprises a third material that is substantially degraded at alater point in time than the second material and has a significantlylower modulus of elasticity than the second material.
 17. Use of aresorbable polymeric mesh implant according to claim 1 in thereconstruction of a soft tissue defect.
 18. Use according to claim 17,wherein the soft tissue defect is an abdominal wall defect.
 19. Useaccording to claim 18, wherein the abdominal wall defect is a resultfrom a hernia.
 20. Use of a resorbable polymeric mesh implant kitaccording to claim 15 in the reconstruction of a soft tissue defect. 21.Use according to claim 20, wherein the soft tissue defect is anabdominal wall defect.
 22. Use according to claim 21, wherein theabdominal wall defect is a result from a hernia.